Howdy! and help!

Welcome to MG's ....I'm going to move your thread to software and also give you some possible fixes.

Login logout loop
Enter the Recovery Console

Boot the system using the Windows XP CD-ROM. In the first screen when the Setup begins, read the instructions press "R" (in the first screen) enter the Recovery Console. Type-in the built-in Administrator password to enter the Console. You'll see the prompt reading C:\Windows (Or any other drive-letter where you've installed XP)

Type the following command and press Enter.

CD SYSTEM32
(If that does not work, try CHDIR SYSTEM32)

COPY USERINIT.EXE WSAUPDATER.EXE

Quit Recovery Console by typing EXIT and restart Windows.

You'll be able to login successfully as you've created the wsaupdater.exe file (now, a copy of userinit.exe)

Now, change the USERINIT value in the registry (see Phase II in this page) and change it accordingly.

Click Start, Run and type REGEDIT. Navigate to:

HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ WindowsNT \ CurrentVersion \ Winlogon

In the right-pane, change the value of Userinit to "C:\WINDOWS\system32\userinit.exe,"

Type the above value exactly as given, including the comma - exclude the quotes. Also, change the path to userinit.exe appropriately if Windows is installed in a different drive.

Close Registry Editor and restart Windows. The Quick Launch settings should be retained now.